Graphical QR Code Scan Response Improvements

[grablair]

This does the following:

1. Removes some dead, duplicated code
2. Adds alternate, temporary QR code outline colors, depending upon the context
   1. Yellow: Check-In is in-progress. This color is activated when the check-in call is sent, then deactivates as soon as it receives a response.
   2. Green: Check-In succeeded. This color is activated when the check-in call comes back successful, the attendee was not already checked in, and will remain on for half a second.
   3. Red: Check-In failed. This color is activated when either the check-in call comes back with a failure, or the attendee was already checked in, and will remain on for half a second.

Checklist

• I have read the contributing guidelines.
• My code is of good quality and follows the coding standards of the project.
• I have tested my changes, and they work as expected.

Thank you for your contribution! 🎉

[daveearley]

Nice! Thanks for this :-) Tested and it works well.